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Gardening News

April
2012

 

 

 

By
Rosie Lerner

Consumer Horticulture Specialist
Purdue University

 

04-05-12

Question and Answer


rhubarb bloom
Rhubarb bolting (flowering)

Q. My rhubarb plant has been blooming and I have been cutting them off, but recently heard that rhubarb leaves are poisonous. Are the flowers poisonous, too? Do I need to wear gloves? What causes them to bloom?

A. The flowers (and the leafy foliage) of rhubarb plant are toxic if ingested, but not generally considered a skin toxin. However, some do find the sap an irritant, so it's always a good idea to wear gloves when gardening. More information about rhubarb toxicity is available at http://www.ppdl.purdue.edu/ppdl/weeklypics/4-13-09.html.

It does appear that some rhubarb plants are more prone to flowering than others. Old-fashioned varieties, such as Victoria and MacDonald, are heavy seed-stalk producers. Canada Red and Valentine are less likely to bolt. Plant maturity is also a factor, with more mature plants being more likely to bolt than youngsters. Dividing the crowns every 4-5 years should help rejuvenate the planting. And, no doubt, weather also plays a role, as it does seem to be more problematic in some years.

box elderQ. We have what I believe to be a box elder in our front yard. I find it to look very similar to poison ivy. I would rather not use herbicide, but I'm leery to pull it up with work gloves on! Do you have any tips? (box elder photos, courtesy of Tom Hankins)

box elderA. You may be relieved to know that these are definitely box elder, known botanically as Acer negundo. Box elder does look a bit like poison ivy, but since it is a species of maple, it has opposite leaves (attached in pairs). Poison ivy has alternate leaf arrangement. Box elder can also be quite the invasive plant with prolific seed production. Here are some links to useful information about this plant, as well as some control strategies.

http://dnr.wi.gov/invasives/fact/wetshrubs_boxelder.htm

http://ohiodnr.com/forestry/trees/box/tabid/5342/Default.aspx

http://www.extension.iastate.edu/forestry/iowa_trees/trees/boxelder.html

Q. My neighbor has a beautiful dogwood tree in bloom right now, and I would love to get a start of it. Is this possible?

A. Flowering dogwood (Cornus florida) is relatively easy to propagate from softwood cuttings taken immediately after flowering has ended. Using a rooting hormone (can be purchased at most garden centers) will greatly improve rooting.

We have extensive information on propagation by cuttings at
http://www.hort.purdue.edu/ext/HO-37web.html

     

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Writer: B. Rosie Lerner

Editor: Olivia Maddox, (765) 496-3207

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Last updated: 10 April 2012

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